The present invention relates generally to a system for preventing accidents in conjunction with machines, and more particularly to an accident prevention system for machines having one or more movable components.
Many machines, such as textile machines (e.g. carding machines and the like) have components which rotate (e.g. drums, shafts, etc.) or which otherwise move and which therefore can cause an accident if a worker or an observer comes in contact with them. To avoid this, such machines are usually provided with protective casings having doors or other elements which can be opened to afford access to the machine, and in many instances in particular to the movable component of the same. If, however, the door or other element of the casing or protective enclosure can be opened while the movable component continues to move, then the danger of accident is restored, i.e. the protective purpose of the enclosure is defeated. For this reason, proposals have been made to assure that the door of the enclosure can be opened only if the movable component is stationary. For example, in German Gebrauchsmuster DE-GM 76 07 709 a device has been suggested in which the core of an electromagnet is tripped by a sensor which detects if a movable component is stationary, i.e. does not perform any movement. Details of the sensor are not disclosed. Movement of the core causes a switch to be released so that it can be manually operated, whereby at the same time an angled lever is moved which causes the arresting of an actuating element to be deactivated. The actuating element has a projecting part which serves as a hand grip permitting the shifting of a push rod and in response to such shifting latch components connected with the push rod move out of the path of hooks connected with a protective cover so that the same can be opened. In this construction, however, it is necessary to operate two separate elements manually and these elements are, moreover, mechanically linked with one another so that the unlatching of several spaced-apart safety devices--i.e. safety devices on e.g. different machines or machines which are located around a corner from one another--cannot be effected by operating a central switch or the like, or so that at the very least this is possible only by providing a very complicated and therefore expensive construction.